XML 37 R75.htm IDEA: XBRL DOCUMENT v3.20.1
Stock-Based Incentive Compensation Plans and Employee Benefit Plans Plan Assets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Savings Plan [Abstract]      
Defined Contribution Plan, Cost $ 58 $ 43 $ 41
Postemployment Benefits [Abstract]      
Postemployment Benefits, Period Expense 2 3 6
Other Non-Qualified Plans [Abstract]      
Benefit expense related to deferred compensation plans 4 $ 3 $ 3
Non-qualified Pension Plan [Member]      
Total contributions to the plans during the period 23    
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year $ 7    
Pension Plan [Member]      
Discount Rate 3.20% 4.35% 3.65%
Plan assets, fair value $ 2,005 $ 1,516 $ 1,801
Obligation To Return Cash Received As Collateral From Securities Lending, (61) (77)  
Defined Benefits Plan, Fair Value Of Plan Assets, Excluding Investments Measured at Net Asset Value 1,339 860  
Defined Benefit Plan, Contribution by Employer, Qualified Plan 86    
Total contributions to the plans during the period 109 $ 69  
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year 76    
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
Pension benefit payments 2020 180    
Pension benefit payments 2021 178    
Pension benefit payments 2022 180    
Pension benefit payments 2023 181    
Pension benefit payments 2024 177    
Pension benefit payments 2025 - 2029 $ 824    
Other Non-Qualified Plans [Abstract]      
Annualized individual discount rates based on time period, minimum 6 months    
Annualized individual discount rates based on time period, maximum 99 years    
Postretirement Benefits [Member]      
Discount Rate 3.25% 4.35% 3.60%
Plan assets, fair value $ 128 $ 114 $ 120
Total contributions to the plans during the period 17 14  
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year 17    
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
Pension benefit payments 2020 18    
Pension benefit payments 2021 18    
Pension benefit payments 2022 19    
Pension benefit payments 2023 20    
Pension benefit payments 2024 21    
Pension benefit payments 2025 - 2029 $ 112    
Other Non-Qualified Plans [Abstract]      
Annualized individual discount rates based on time period, minimum 6 months    
Annualized individual discount rates based on time period, maximum 99 years    
Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value $ 564 442  
Obligation To Return Cash Received As Collateral From Securities Lending, (61) (77)  
Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 775 418  
Obligation To Return Cash Received As Collateral From Securities Lending, 0 0  
Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Obligation To Return Cash Received As Collateral From Securities Lending, 0 0  
U.S. Equity [Member] | Pension Plan [Member]      
Plan assets, fair value 69 60  
U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value 69 60  
U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Cash and Cash Equivalents [Member] | Pension Plan [Member]      
Plan assets, fair value (7) 19  
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value (7) 19  
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Investment grade or above [Member] | Pension Plan [Member]      
Plan assets, fair value 699 368  
Investment grade or above [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Investment grade or above [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 699 368  
Investment grade or above [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Cash received as collateral from securities [Member] | Pension Plan [Member]      
Plan assets, fair value 61 77  
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value 61 77  
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
U.S. treasuries [Member] | Pension Plan [Member]      
Plan assets, fair value 232 196  
U.S. treasuries [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value 232 196  
U.S. treasuries [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
U.S. treasuries [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Mortgage backed securities [Member] | Pension Plan [Member]      
Plan assets, fair value 8 6  
Mortgage backed securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Mortgage backed securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 8 6  
Mortgage backed securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Asset backed securities [Member] | Pension Plan [Member]      
Plan assets, fair value 3 1  
Asset backed securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Asset backed securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 3 1  
Asset backed securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Municipal bonds [Member] | Pension Plan [Member]      
Plan assets, fair value 44 27  
Municipal bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Municipal bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 44 27  
Municipal bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Mutual funds [Member] | Pension Plan [Member]      
Plan assets, fair value 270 167  
Mutual funds [Member] | Postretirement Benefits [Member]      
Plan assets, fair value $ 128 $ 114  
Mutual funds [Member] | International Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 31.00% 85.00%  
Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 8.00% 7.00%  
Mutual funds [Member] | U.S. Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 49.00% 15.00%  
Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 21.00% 19.00%  
Mutual funds [Member] | Real Estate Funds [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 1.00% 0.00%  
Mutual funds [Member] | Fixed Income Funds [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 19.00% 0.00%  
Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 71.00% 74.00%  
Mutual funds [Member] | Emerging Market Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage   34.00%  
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value $ 270 $ 167  
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value 128 114  
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value 0 0  
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value 0 0  
International government bonds [Member] | Pension Plan [Member]      
Plan assets, fair value 21 16  
International government bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
International government bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]      
Plan assets, fair value 21 16  
International government bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]      
Plan assets, fair value 0 0  
Common Collective Trust Funds [Member] | Pension Plan [Member]      
Plan assets, fair value $ 666 $ 656  
Common Collective Trust Funds [Member] | International Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 29.00% 41.00%  
Common Collective Trust Funds [Member] | U.S. Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 51.00% 5.00%  
Common Collective Trust Funds [Member] | Real Estate Funds [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 6.00% 0.00%  
Common Collective Trust Funds [Member] | Fixed Income Funds [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 14.00% 54.00%  
Common Collective Trust Funds [Member] | Emerging Market Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage   4.00%  
Benefit Obligation [Member]      
Postemployment Benefits [Abstract]      
Postemployment benefit obligations $ 11 $ 11  
Other Non-Qualified Plans [Abstract]      
Other non-qualified plans benefit obligations deferred compensation 41 42  
Benefit obligations related to split-dollar life insurance arrangements $ 32 36  
Minimum [Member] | U.S. Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 19.00%    
Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 13.00%    
Minimum [Member] | International Developed Market Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 8.00%    
Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 3.00%    
Minimum [Member] | Real Estate Funds [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 3.00%    
Minimum [Member] | Fixed Income [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 52.00%    
Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 69.00%    
Minimum [Member] | Cash and Cash Equivalents [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 0.00%    
Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 0.00%    
Maximum [Member] | U.S. Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 29.00%    
Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 23.00%    
Maximum [Member] | International Developed Market Equity [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 18.00%    
Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 13.00%    
Maximum [Member] | Real Estate Funds [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 9.00%    
Maximum [Member] | Fixed Income [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 62.00%    
Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 79.00%    
Maximum [Member] | Cash and Cash Equivalents [Member] | Pension Plan [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 2.00%    
Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 2.00%    
Common Stock [Member] | CenterPoint Energy [Member]      
Savings Plan [Abstract]      
Number of Common stock held by the savings plan (in shares) 11,051,800    
Percentage of investment in common stocks (in hundredths) 13.00%    
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage 25.00%    
CenterPoint Energy Houston Electric, LLC      
Savings Plan [Abstract]      
Defined Contribution Plan, Cost $ 18 17 17
Postemployment Benefits [Abstract]      
Postemployment Benefits, Period Expense 1 4 1
Other Non-Qualified Plans [Abstract]      
Benefit expense related to deferred compensation plans 1 $ 1 $ 1
CenterPoint Energy Houston Electric, LLC | Non-qualified Pension Plan [Member]      
Total contributions to the plans during the period 0    
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year 0    
CenterPoint Energy Houston Electric, LLC | Pension Plan [Member]      
Defined Benefit Plan, Contribution by Employer, Qualified Plan 0    
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year $ 0    
CenterPoint Energy Houston Electric, LLC | Postretirement Benefits [Member]      
Discount Rate 3.25% 4.35% 3.60%
Plan assets, fair value $ 101 $ 89 $ 93
Total contributions to the plans during the period 10 9  
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year 9    
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
Pension benefit payments 2020 8    
Pension benefit payments 2021 8    
Pension benefit payments 2022 9    
Pension benefit payments 2023 10    
Pension benefit payments 2024 10    
Pension benefit payments 2025 - 2029 $ 54    
Other Non-Qualified Plans [Abstract]      
Annualized individual discount rates based on time period, minimum 6 months    
Annualized individual discount rates based on time period, maximum 99 years    
CenterPoint Energy Houston Electric, LLC | Mutual funds [Member] | Postretirement Benefits [Member]      
Plan assets, fair value $ 101 $ 89  
CenterPoint Energy Houston Electric, LLC | Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 8.00% 7.00%  
CenterPoint Energy Houston Electric, LLC | Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 21.00% 19.00%  
CenterPoint Energy Houston Electric, LLC | Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 71.00% 74.00%  
CenterPoint Energy Houston Electric, LLC | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value $ 101 $ 89  
CenterPoint Energy Houston Electric, LLC | Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value 0 0  
CenterPoint Energy Houston Electric, LLC | Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value 0 0  
CenterPoint Energy Houston Electric, LLC | Benefit Obligation [Member]      
Postemployment Benefits [Abstract]      
Postemployment benefit obligations 3 3  
Other Non-Qualified Plans [Abstract]      
Other non-qualified plans benefit obligations deferred compensation 8 9  
Benefit obligations related to split-dollar life insurance arrangements $ 1 1  
CenterPoint Energy Houston Electric, LLC | Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 13.00%    
CenterPoint Energy Houston Electric, LLC | Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 3.00%    
CenterPoint Energy Houston Electric, LLC | Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 69.00%    
CenterPoint Energy Houston Electric, LLC | Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 0.00%    
CenterPoint Energy Houston Electric, LLC | Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 23.00%    
CenterPoint Energy Houston Electric, LLC | Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 13.00%    
CenterPoint Energy Houston Electric, LLC | Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 79.00%    
CenterPoint Energy Houston Electric, LLC | Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 2.00%    
CenterPoint Energy Houston Electric, LLC | Common Stock [Member] | CenterPoint Energy [Member]      
Savings Plan [Abstract]      
Number of Common stock held by the savings plan (in shares) 11,051,800    
Percentage of investment in common stocks (in hundredths) 13.00%    
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage 25.00%    
CenterPoint Energy Resources Corp.      
Savings Plan [Abstract]      
Defined Contribution Plan, Cost $ 18 18 17
Postemployment Benefits [Abstract]      
Postemployment Benefits, Period Expense 1 1 4
Other Non-Qualified Plans [Abstract]      
Benefit expense related to deferred compensation plans 0 $ 0 $ 0
CenterPoint Energy Resources Corp. | Non-qualified Pension Plan [Member]      
Total contributions to the plans during the period 0    
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year 0    
CenterPoint Energy Resources Corp. | Pension Plan [Member]      
Defined Benefit Plan, Contribution by Employer, Qualified Plan 0    
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year $ 0    
CenterPoint Energy Resources Corp. | Postretirement Benefits [Member]      
Discount Rate 3.25% 4.35% 3.60%
Plan assets, fair value $ 27 $ 25 $ 26
Total contributions to the plans during the period 3 4  
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year 3    
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
Pension benefit payments 2020 5    
Pension benefit payments 2021 4    
Pension benefit payments 2022 5    
Pension benefit payments 2023 5    
Pension benefit payments 2024 6    
Pension benefit payments 2025 - 2029 $ 30    
Other Non-Qualified Plans [Abstract]      
Annualized individual discount rates based on time period, minimum 6 months    
Annualized individual discount rates based on time period, maximum 99 years    
CenterPoint Energy Resources Corp. | Mutual funds [Member] | Postretirement Benefits [Member]      
Plan assets, fair value $ 27 $ 25  
CenterPoint Energy Resources Corp. | Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 7.00% 6.00%  
CenterPoint Energy Resources Corp. | Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 24.00% 21.00%  
CenterPoint Energy Resources Corp. | Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage 69.00% 73.00%  
CenterPoint Energy Resources Corp. | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value $ 27 $ 25  
CenterPoint Energy Resources Corp. | Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value 0 0  
CenterPoint Energy Resources Corp. | Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]      
Plan assets, fair value 0 0  
CenterPoint Energy Resources Corp. | Benefit Obligation [Member]      
Postemployment Benefits [Abstract]      
Postemployment benefit obligations 7 7  
Other Non-Qualified Plans [Abstract]      
Other non-qualified plans benefit obligations deferred compensation 3 3  
Benefit obligations related to split-dollar life insurance arrangements $ 0 $ 0  
CenterPoint Energy Resources Corp. | Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 15.00%    
CenterPoint Energy Resources Corp. | Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 2.00%    
CenterPoint Energy Resources Corp. | Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 68.00%    
CenterPoint Energy Resources Corp. | Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 0.00%    
CenterPoint Energy Resources Corp. | Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 25.00%    
CenterPoint Energy Resources Corp. | Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 12.00%    
CenterPoint Energy Resources Corp. | Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 78.00%    
CenterPoint Energy Resources Corp. | Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 2.00%    
CenterPoint Energy Resources Corp. | Common Stock [Member] | CenterPoint Energy [Member]      
Savings Plan [Abstract]      
Number of Common stock held by the savings plan (in shares) 11,051,800    
Percentage of investment in common stocks (in hundredths) 13.00%    
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage 25.00%